SCS is a type of neurostimulation intended to manage chronic pain, particularly within the back, neck, arms or legs, particularly neuropathic pain, i.e. pain marked by burning, tingling or numbness. Benefits of SCS or other forms of neurostimulation may include: a reduction in pain; a reduction or elimination of the use of pain medications; and increased activity levels and an improved overall quality of life. Neurostimulation has been used to manage pain that comes from failed back surgery syndrome (FBSS) or post-laminectomy syndrome and other neuropathies. Neurostimulation operates by intercepting pain signals before they reach the brain. To this end, a small SCS system may be implanted within the body to deliver electrical pulses to nerves along the spinal cord. Some patients describe the resulting sensation as a gentle massaging sensation or, in some cases, simply the absence of pain. The SCS system typically includes a small generator device, similar to a pacemaker, equipped to send electrical pulses to leads mounted along the nerves near the spinal cord. The generator is usually implanted in the abdomen or buttock area. The stimulation leads include either thin wires or paddles for delivering pulses from the generator to the nerves along the spinal cord. Thin wire leads, also referred to as percutaneous leads, are implanted within the epidural space using a special needle. Paddle leads are instead typically implanted during a surgical procedure where a small amount of bone is removed from one of the vertebra. An external programmer device, similar to a remote control, is provided to allow the patient to control or adjust the stimulation.
SCS is an approved treatment for chronic pain and intractable angina pectoris. Preclinical and clinical studies have shown that SCS has cardioprotective effects. Long term SCS has been shown to protect against ventricular arrhythmias and also improve left ventricular function. See, for example, DeJongste, “Spinal cord stimulation for ischemic heart disease” Neurol Res 2000; 22(3):293-298; Sanderson et al., “Spinal electrical stimulation for intractable angina—long-term clinical outcome and safety” Eur Heart J 1994; 15(6):810-814; Foreman et al. “Modulation of intrinsic cardiac neurons by spinal cord stimulation: implications for its therapeutic use in angina pectoris” Cardiovasc Res 2000; 47(2):367-375; Olgin et al., “Effects of Thoracic Spinal Cord Stimulation on Cardiac Autonomic Regulation of the Sinus and Atrioventricular Nodes” J Cardiovasc Electrophysiol 2002; 13(5):475-481; Issa et al., “Thoracic Spinal Cord Stimulation Reduces the Risk of Ischemic Ventricular Arrhythmias in a Postinfarction Heart Failure Canine Model” Circulation 2005; 111(24):3217-3220; and Lopshire et al., “Spinal Cord Stimulation Improves Ventricular Function and Reduces Ventricular Arrhythmias in a Canine Postinfarction Heart Failure Model” Circulation 2009; 120:286-294. Numerous other papers discussing the effects of SCS on cardiac disorders are available in the medical literature.
Generally, SCS can have positive or negative effects including differing regional effects within various heart tissues and chambers. Accordingly, it would be desirable to control the operation of the SCS device (or other neurostimulation device) to enhance any positive effects and to eliminate or mitigate any negative effects, preferably on a regional basis. Patients with implantable SCS devices may also have CRMDs implanted therein such as pacemakers, implantable cardioverter/defibrillators (ICDs) and cardiac resynchronization therapy devices (CRTs). Accordingly, it would be particularly desirable to provide techniques for allowing the CRMD to assess any regional effects on the heart arising due to SCS and to then adjust SCS therapy so as to enhance positive effects and eliminate or mitigate negative effects. It is to this end that various aspects of the invention are generally directed.